1. Field of the Invention
The present invention relates to a communication terminal device having an error correction function defined by ITU-T Recommendations T.30.
2. Description of the Related Art
The communication method with an error correction function (referred to as ECM communication) (ECM: Error Correction Method) defined in ITU-T Recommendation T.30 is a way of communication that sends and receives image data in blocks, each block including a plurality of frames, and when a communication error occurs in a particular frame, repeatedly sends that frame to a recipient until transmission of an entire block including that frame succeeds. The ECM communication is often utilized in facsimile communication to foreign countries since communication errors likely happen in overseas communication.
A typical conventional communication terminal device simply lowers a communication speed with the same modulation method when line irregularity is detected several times during the ECM communication. Retransmitting data with the reduced communication speed sometimes results in successful data transmission. However, the communication errors may continue even if the communication speed is reduced as far as the communication terminal device employs a certain type of modem of which eye is designed to diverge unless resetting is performed after occurrence of the eye pattern. In particular, the communication speed reduction does not work once the eye pattern diverges in a detected voltage wave form if such modem is employed.